Problem detection apparatus

Abstract

A problem detection apparatus includes a relay, a measurement circuit and a controller. The relay is provided between a power supply and an external circuit, both of which are in a high voltage system. The relay is configured to switch an electrical connection state of the power supply to the external circuit between a closed state and an open state. The measurement circuit measures a voltage of a circuit in the high voltage system. The measurement circuit is in the high voltage system and connected between the relay and the external circuit. In a case where a command to switch the relay to the open state has been output, the controller detects, based on the voltage measured by the measurement circuit, whether or not the relay has a short circuit. The controller is in a low voltage system having a lower voltage than a voltage of the high voltage system.

What is claimed is: 
     
       1. An abnormality detection apparatus comprising:
 a relay that is provided between a power supply and an external circuit, both of which are in a high voltage system, the relay configured to switch an electrical connection state of the power supply to the external circuit between a closed state and an open state; 
 a measurement circuit that measures a voltage of a circuit in the high voltage system, the measurement circuit being in the high voltage system and being connected between the relay and the external circuit; and 
 a controller that determines whether the relay has a short circuit based on the voltage measured by the measurement circuit when the controller outputs a command signal to switch the relay to the open state, the controller being in a low voltage system having a lower voltage than a voltage of the high voltage system, wherein 
 the circuit in the high voltage system branches into a plurality of circuits each of which has a corresponding measurement circuit; 
 each of the corresponding measurement circuits is connected between the relay and the external circuit; 
 the corresponding measurement circuits measure voltages of each of the plurality of circuits; and 
 when the controller outputs the command signal to switch the relay to the open state, the controller determines whether the relay has the short circuit based on the voltages measured by the corresponding measurement circuits. 
 
     
     
       2. The abnormality detection apparatus according to  claim 1 , wherein
 the measurement circuit also is configured to monitor a voltage of the power supply. 
 
     
     
       3. The abnormality detection apparatus according to  claim 2 , wherein
 the corresponding measurement circuits are connected in series and monitor voltages of battery blocks that are connected in series, and 
 the circuit in the high voltage system includes a circuit component that prevents a current from flowing from one of the corresponding measurement circuits having a higher reference potential to one of the corresponding measurement circuits having a lower reference potential. 
 
     
     
       4. The abnormality detection apparatus according to  claim 3 , wherein
 the voltage measured by the corresponding measurement circuit having the higher reference potential is adjusted based on the voltage measured by the corresponding measurement circuit having the lower reference potential. 
 
     
     
       5. The abnormality detection apparatus according to  claim 2 , wherein
 the circuit in the high voltage system includes one or more resistors that restrict a voltage that is applied to the corresponding measurement circuits. 
 
     
     
       6. The abnormality detection apparatus according to  claim 1 , wherein
 the relay includes: a first relay that is provided between a positive electrode of the power supply and the external circuit; and a second relay that is provided between a negative electrode of the power supply and the external circuit; 
 the circuit in the high voltage system includes: a first circuit that is connected between the first relay and the external circuit; and a second circuit that is connected between the second relay and the external circuit; 
 the measurement circuit measures a voltage of the first circuit and a voltage of the second circuit; and 
 the controller determines: (i) whether the first relay has the short circuit based on the voltage of the first circuit measured by the measurement circuit when the controller outputs the command signal to switch the first relay to the open state; and (ii) whether the second relay has the short circuit based on the voltage of the second circuit measured by the measurement circuit when the controller outputs the command signal to switch the second relay to the open state. 
 
     
     
       7. The abnormality detection apparatus according to  claim 6 , wherein
 when the controller outputs the command signal to switch the second relay to the open state, the controller determines whether the second relay has the short circuit based on the voltage measured by the measurement circuit while the second circuit is being applied with a predetermined voltage. 
 
     
     
       8. The abnormality detection apparatus according to  claim 1 , wherein
 the measurement circuit measures the voltage of the circuit while a predetermined voltage is being applied to the circuit having the relay switched to the open state in the high voltage system, and 
 the controller performs a failure diagnosis for the circuit in the high voltage system, based on the voltage measured by the measurement circuit while the predetermined voltage is being applied to the circuit in the high voltage system. 
 
     
     
       9. The abnormality detection apparatus according to  claim 8 , wherein
 corresponding measurement circuits are connected in series, and monitor voltages of battery blocks connected in series; 
 the circuit in the high voltage system includes a circuit component that prevents a current from flowing from one of the corresponding measurement circuits having a higher reference potential to one of the corresponding measurement circuits having a lower reference potential; and 
 the predetermined voltage is applied between the circuit component and the corresponding measurement circuit having the lower reference potential. 
 
     
     
       10. An assembled battery system comprising:
 an assembled battery that is comprised of battery blocks connected in series; 
 a relay that is provided between the assembled battery and an external circuit, both of which are in a high voltage system, the relay configured to switch an electrical connection state of the assembled battery to the external circuit between a closed state and an open state; 
 a measurement circuit that measures a voltage of a circuit in the high voltage system, the measurement circuit being in the high voltage system and being connected between the relay and the external circuit; and 
 a controller that determines whether the relay has a short circuit based on the voltage measured by the measurement circuit when the controller outputs a command signal to switch the relay to the open state, the controller being in a low voltage system having a lower voltage than a voltage of the high voltage system, wherein 
 the circuit in the high voltage system branches into a plurality of circuits each of which has a corresponding measurement circuit; 
 each of the corresponding measurement circuits is connected between the relay and the external circuit; 
 the corresponding measurement circuits measure voltages of each of the plurality of circuits; and 
 when the controller outputs the command signal to switch the relay to the open state, the controller determines whether the relay has the short circuit based on the voltages measured by the corresponding measurement circuits.